[pgpool-general: 430] Re: strange load balancing issue in Solaris

[Aravinth]

Sorry . I missed it.

Here is the log file.

--Aravinth


On Wed, May 9, 2012 at 2:07 PM, Tatsuo Ishii <ishii at postgresql.org> wrote:

> > The code you have sent is same in child.c.
>
> No.
>
>        pool_log("r: %f total_weight: %f", r, total_weight);
>
> You need to add the line above to get usefull information.
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
>
>
> > I have attached the log file. Please check
> >
> >
> > --Aravinth
> >
> >
> > On Tue, May 8, 2012 at 6:20 AM, Tatsuo Ishii <ishii at postgresql.org>
> wrote:
> >
> >> I suspect there's some portablity issue with load balance code. The
> >> actual source code is in select_load_balancing_nodechild.c).
> >> Please modify source code and connect to pgpool by using psql.
> >> Please send the log output.
> >> --
> >> Tatsuo Ishii
> >> SRA OSS, Inc. Japan
> >> English: http://www.sraoss.co.jp/index_en.php
> >> Japanese: http://www.sraoss.co.jp
> >>
> >> int select_load_balancing_node(void)
> >> {
> >>        int selected_slot;
> >>        double total_weight,r;
> >>        int i;
> >>
> >>        /* choose a backend in random manner with weight */
> >>        selected_slot = MASTER_NODE_ID;
> >>        total_weight = 0.0;
> >>
> >>        for (i=0;i<NUM_BACKENDS;i++)
> >>        {
> >>                if (VALID_BACKEND(i))
> >>                {
> >>                        total_weight += BACKEND_INFO(i).backend_weight;
> >>                }
> >>        }
> >>        r = (((double)random())/RAND_MAX) * total_weight;
> >>        pool_log("r: %f total_weight: %f", r, total_weight);
>  <--
> >> add this
> >>
> >>        total_weight = 0.0;
> >>        for (i=0;i<NUM_BACKENDS;i++)
> >>        {
> >>                if (VALID_BACKEND(i) && BACKEND_INFO(i).backend_weight >
> >> 0.0)
> >>                {
> >>                        if(r >= total_weight)
> >>                                selected_slot = i;
> >>                        else
> >>                                break;
> >>                        total_weight += BACKEND_INFO(i).backend_weight;
> >>                 }
> >>        }
> >>
> >>        pool_debug("select_load_balancing_node: selected backend id is
> %d",
> >> selected_slot);
> >>         return selected_slot;
> >> }
> >>
> >>
> >> > Hi Tatsuo, Thanks for the reply.
> >> >
> >> > The normalized weights are 0.5 for both nodes and the selected node is
> >> always the same node. I hope then it's srandom().
> >> >
> >> >
> >> > Any idea to solve this srandom issue
> >> >
> >> >
> >> > Thanks and Regards,
> >> > Aravinth
> >> >
> >> >
> >> > ________________________________
> >> >  From: Tatsuo Ishii <ishii at postgresql.org>
> >> > To: aravinth at mafiree.com
> >> > Cc: pgpool-general at pgpool.net
> >> > Sent: Tuesday, May 1, 2012 4:41 AM
> >> > Subject: Re: [pgpool-general: 396] strange load balancing issue in
> >> Solaris
> >> >
> >> > First of all please check "normalized" weights are as you expected.
> >> > Run "show pool_status;" and see "backend_weight0", "backend_weight1"
> >> > section. You see a floating point numbers, which are the normalized
> >> > weight between 0.0 and 1.0. If you see both are 0.5, primary and
> >> > standby are given same weight.
> >> >
> >> > If they are ok, I suspect srandom() function behavior is different
> >> > from other platforms. Pgpool-II chooses the load balance node by using
> >> > srandom(). select_load_balancing_node() is the function which is
> >> > responsible for selecting the load balance node. If you run pgpool-II
> >> > with -d (debug) option, you will see following in the log:
> >> >
> >> >     pool_debug("select_load_balancing_node: selected backend id is
> %d",
> >> selected_slot);
> >> >
> >> > If backend_weight in show pool_status are fine but the line above
> >> > always shows same number, it is the sign that we have problem with
> >> > srandom().
> >> > --
> >> > Tatsuo Ishii
> >> > SRA OSS, Inc. Japan
> >> > English: http://www.sraoss.co.jp/index_en.php
> >> > Japanese: http://www.sraoss.co.jp
> >> >
> >> >> Hi All,
> >> >>
> >> >> I am facing a strange issue in load balancing with replication mode
> set
> >> to
> >> >> true in Solaris. Load balancing algorithm always select the same node
> >> >> whatever may be the backend weight
> >> >>
> >> >> Here is the scenario.
> >> >>
> >> >> I have a pgpool installed installed in 1 server
> >> >> 2 postgres nodes in other 2 servers
> >> >> replication mode set to true and load balancing set to true
> >> >> backend weight of the 2 nodes is 1.
> >> >>
> >> >> When I fire the queries manuall using different connections or using
> >> >> pgbench all the queries hit the same node. Load balancing algorithm
> >> always
> >> >> select the same node.
> >> >> No effect in changing the backend weight. Only when I set backend
> >> weight to
> >> >> 0 hits go to the other server.
> >> >>
> >> >>
> >> >> I face this issue only in solaris. The same setup in other servers (
> >> centos
> >> >> ,RHEL, ubunt etc) does the load balancing perfectly.
> >> >>
> >> >> Also tries various postgres versions and pgpool version with same
> >> result.
> >> >> But every version runs fine in other servers.
> >> >>
> >> >> Has anyone faced this issue?
> >> >>
> >> >> Any information would highly helpful.
> >> >>
> >> >> Regards,
> >> >> Aravinth
> >> _______________________________________________
> >> pgpool-general mailing list
> >> pgpool-general at pgpool.net
> >> http://www.pgpool.net/mailman/listinfo/pgpool-general
> >>
>
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